Abrasive finishing apparatus



Nov. 22, 1966 G. H. LOCKWOOD 3,

ABRASIVE FINISHING APPARATUS Filed March 4, 1964 INVENTOR.

George H. loclzwood H eq 7 United States Patent ration of Delaware FiledMar. 4, 1964, Ser. No. 349,303 7 Claims. (Cl. 5133) I This inventionrelates to an abrasive finishing apparatus and, more particularly, toapparatus arranged to refine a surface of revolution by the abrasiveprocess.

In the art of honing annular surfaces, such as the grooves in the racesof ball bearings, it has been found that, for a reason not clearlyunderstood, when one attempts to speed up the finishing operation byremoving large amounts of material, the surface tends to take a shapewhich is not entirely concentric with the axis of revolution. Thiscondition i known as being out of round and is a serious limitation onthe ability to speed up production, particularly in automatic machinesof this type. These and other difiiculties experienced with the priorart devices have been obviated in a novel manner by the presentinvention.

It is, therefore, an outstanding object of the invention to provide anabrasive finishing apparatus in which the use of high rates of stockremoval does not result in an out-of-round condition in the workpiece.

Another object of this invention is the provision of an apparatus forhoning annular grooves or the like, wherein the work is carried on at ahigh speed and wherein the finished surface is perfectly concentric withthe axis of the workpiece.

A further object of the present invention is the provision of anapparatus for honing which gives a fine finish to the workpiece, despitea high production rate.

It is another object of the instant invention to provide a honingmachine having a means for improving the concentricity of the finishedsurface, which means is simple and rugged and which is capable of alonglife of useful service with a minimum of attention.

With these and other objects in view, as will be apparent to thoseskilled in the art, the invention resides in the combination of partsset forth in the specification and covered by the claims appendedhereto.

The character of the invention, however, may be best understood byreference to one of its structural forms, as illustrated by theaccompanying drawings in which:

The single figure is a partially sectioned front elevational view of anapparatus embodying the principles of the present invention.

Referring to the drawing, the apparatus, indicated generally by thereference numeral 10, is shown as a honing apparatus of the type shownand described in the copending patent application of Lockwood, SerialNumber 247,094, filed December 26, 1962, for Apparatus for Honing anAnnular Surface, now Patent No. 3,178,858. The principle of operation isthat the workpiece remains fixed, While the honing stones are rotatedabout the axis of the workpiece and, by a reciprocation of the honinghead, the stones are rotated about the center of curvature of thegroove. The apparatus is provided with a base 11 from which extend fourvertical abutments 12, 13, 14, and 15. Fastened to the base at the rearof the machine and extending over the rest of the apparatus is amounting block 16.

Mounted on the abutment 12 is a platen 17 having a flat, vertical face18 which is very carefully machined and against which is pressed one endof a workpiece 19 which, for the purposes of illustration, is shown asthe inner race of a ball bearing, which race has a groove 21 to befinished by honing.

Extending through the abutment 13 is a bore 22 whose "ice axis isaligned with the axis of the workpiece 19, particularly of its innerbore 23. The bore 22 slidably carries a ram 24 which, in turn, carries aspindle 25 on which is mounted a drive pulley 26. On the end of thespindle 25 closest to the workpiece 21 is carried a head 27 on which arepivotally carried at least a plurality of arms 28. Mounted at the outerend of each arm 28 is a honing stone 29 having a suitable curved innersurface for formation and finishing of the groove 21. Within the head 27are provided springs 31 for biasing the arms 28 to press the stones 29inwardly against the surface of the groove 21. The interior of the ram24 is provided with a cylinder 32 in which is slidably carried a piston33 whose rod 34 is connected to the upper part of the abutment 14.Suitable hydraulic connections are made to the cylinder to provide formovement of the ram 24 longitudinally of the axis of the workpiece.Extending through the head 27, the spindle 25, and the ram 24 is a rod35. The end of the rod 35 adjacent the workpiece 19 is provided with aclamping plug 36 having a reduced portion 37 adapted to engage theworkpiece 19 and hold it firmly against the platen 17. The diameter ofthe reduced portion 37 is only slightly less than the diameter of theinner bore 23 of the workpiece, so that the surface 37 engages thesurface of the bore 23 and the clamp plug engages the end of theworkpiece facing toward the head 27. The platen 17 and the clamping plug36 form a fixed workhead.

The rod 35 extends through the abutment 15 and has mounted on it apiston 38 which is slidably carried in a cylinder 39 formed in theabutment. Suitable hydraulic connections are made for moving the piston38 within the cylinder 39, on occasion. At its outer end, the rod 35carries a collar 41. Firmly fixed to the right-hand end of the ram 24 isa plate 42 in which is slidably carried a rod 43 having a rounded head44. The rod 43 is slidably carried in a bearing 45 mounted on anextension 46 of the mounting block 16. Bolted to the end of the rod 43opposite the head 44 isan arm 47 having a bore 48 through which the rod35 slides. Also pivoted on the mounting block 16 is an arm 49 having atits lower end a hardened metal insert 51 adapted to engage the head 44of the shaft 43. At an intermediate position, the arm 49 is providedwith a cam follower 52. The mounting block 16 is also provided With anextension 53 on which is rotatably carried a shaft 54 carrying a cam 55.The shaft 54 and the cam 55 are driven by a motor (not shown).

The operation of the apparatus will now be readily understood in view ofthe above description. Pressure oil provided at the right-hand side ofthe piston 38 in the cylinder 39 forces the rod 35 to the left so thatthe radial surface of the plug 36 presses against the workpiece 19 andholds it tightly against the vertical surf-ace 18 of the platen 17 Thisclamping is such as to prevent the workpiece 19 from rotating and yettakes place without any distortion of the workpiece, since the clampingpressure is equal around the periphery of the workpiece. By means of thepulley 26, the spindle 25 and the head 27 are rotated about the axis ofthe workpiece and the springs 31 press the honing stones 29 against thesurface of the groove 21 to form the finished surface. The ram 24 isreciprocated by the action of the cam 55 on the plate 42. The dimensionsselected are such that the honing stones 29 are rotated about theircenters of curvature in the manner shown and described in Patent No.3,178,858, discussed above. As the ram 24 reciprocates, the plate 42slides over the rod 43, the rod 43 taking part in this action. When theworkpiece is finished and is ready to be exchanged for anotherunfinished workpiece, suitable hydraulic fluid is admitted into thecylinder 39 to withdraw the rod 35 axially away from the workpiece toloosen it and permit its removal. At that time, the ram 24 has beensubjected by the cylinder 32 to an extended retraction also, so that thestones 29 and the arms 28 are removed from the workpiece to permit itsremoval.

Now, the cam 55 is rotated at a selected speed and the ram 24reciprocates back and forth every time the cam makes one revolution.When the portion of greatest throw of the cam extends to the right, theram 24 is moved to the right. That is to say, the cam presses againstthe cam follower 52 which, in turn, presses the insert 51 of the arm 49against the head 44 of the rod 43, so that the rod is held tightlyagainst the plate 42 and moves to the right with the ram 24. The rod 43moving to the right carries the plate 47 and, eventually, the platecontacts the collar 41 on the rod 35. The contact with the rod isselected to be very slight and only momentary, so that the rod 35 isstruck a blow and, despite the presence of oil at the right side of thepiston 38, the rod is pulled slightly to the right, loosening thepressure of the plug 36 against the workpiece. Momentarily, therefore,the workpiece is free to rotate. The head 27 continues to rotate and thereduced portion 37 acts as a support for the workpiece. The stones 29,by their abrasive action, cause the workpiece to rotate slightly. Theram 24 is moved to the left again and almost immediately the rod 43 andthe plate 47 are withdrawn from the collar 41 so that the clamping plug37 is moved back into clamping position against the workpiece 19. Theslight release of the clamp plug 36 in this manner, however, permits theworkpiece 19 to rotate and index slightly during the period of release.The result is that, despite high pressures of the honing stones 29against the surface of the groove 21 and consequent high material rateremoval, the finished surface of the groove is not out-of-round. Aperfectly smooth concentric finished annular surface is obtained.

It is obvious that minor changes may be made in the form andconstruction of the invention without departing from the material spiritthereof. It is not, however, desired to confine the invention to theexact form herein shown and described, but it is desired to include allsuch as properly come Within the scope claimed.

The invention having been thus described, what is claimed as new anddesired to secure by Letters Patent is:

1. Apparatus for honing an annular surface of a workpiece, comprising(a) a fixed workhead having a clamp for holding the workpiece againstrotation,

(b) a toolhead mounted adjacent the workhead and having a spindle whichis subject to rotation about and reciprocation substantially along themajor axis of the said surface, the toolhead pressing a tool against thesurface with a predetermined pressure, and

(c) means operative on the said clamp for releasing the workpieceoccasionally for a short period of time to permit slight rotationthereof.

2. Apparatus as recited in claim 1, wherein the said means includes aneccentric member which provides synchronous reciprocation of thespindle.

3. Apparatus as recited in claim 1, wherein the clamp is mounted on arod which extends through the spindle and is provided with an actuatorfor moving the rod longitudinally to clamp and unclamp the workpiece.

4. Apparatus as recited in claim 3, wherein the rod is provided with acollar and wherein the said means strikes the collar a blow on occasionto overcome the operation of the actuator and to release the workpiece.

5. Apparatus as recited in claim 4, wherein the means is time-d tostrike the collar during each reciprocation of the spindle.

6. Apparatus as recited in claim 5, wherein a second rod is mountedparallel to the clamp rod and extends through a portion of the toolhead,the second rod having a head on one end and a plate at the other inposition to strike the said collar, and wherein an eccentric is providedwhich operates during each reciprocation of the spindle to move the headof the second rod relative to the said portion of the toolhead so thatthe rod reciprocates with the spindle and the plate strikes the collar.

7. Apparatus for finishing an annular surface of a workpiece byabrasion, comprising (a) a workhead having a clamp for holding theworkpiece,

(b) a toolhead mounted adjacent the workhead and having a spindle whichis subject to rotation about and reciprocation substantially along themajor axis of the said surface, the toolhead pressing a tool against thesurface with a predetermined pressure, an

(c) means operative on the said clamp for releasing the workpieceoccasionally for a short period of time to permit a slight rotationthereof.

References Cited by the Examiner UNITED STATES PATENTS 3,178,858 4/1965Lockwood s1 33 LESTER M. SWINGLE, Primary Examiner.

7. APPARATUS FOR FINISHING AN ANNULAR SURFACE OF A WORKPIECE BYABRASION, COMPRISING (A) A WORKHEAD HAVING A CLAMP FOR HOLDING THEWORKPIECE, (B) A TOOLHEAD MOUNTED ADJACENT THE WORKHEAD AND HAVING ASPINDLE WHICH IS SUBJECT TO ROTATION ABOUT AND RECIPROCATIONSUBSTANTIALLY ALONG THE MAJOR AXIS OF THE SAID SURFACE, THE TOOLHEADPRESSING A TOOL AGAINST THE SURFACE WITH A PREDETERMINED PRESSURE, AND(C) MEANS OPERATIVE ON SAID CLAMP FOR RELEASING THE WORKPIECEOCCASIONALLY FOR A SHORT PERIOD OF TIME TO PERMIT A SLIGHT ROTATIONTHEREOF.